The widespread ability of consumers to receive, share, and play back media content over computer networks poses an enormous challenge to content providers. Without any use of encryption or other digital rights management techniques, it is, in principle, a trivial matter for a single copy of media content to be shared among innumerable users, each of whom can create a copy and, in turn, share that copy with others. Even if the first consumer has paid to access the media content, each consumer who receives a shared copy for free may be less likely to pay the content provider for a copy. Moreover, alterations of the copies are possible, such that consumers may receive adulterated content when they believe they are receiving an exact duplicate of the original content. The adulterated content may be of inferior quality, it may include inaccurate attributions of authorship or ownership, or it may even pose security risks to the consumer.
Several systems have been developed to help ensure that content providers can be adequately compensated in proportion to the use of their content, and that consumers receive trustworthy content. Such systems are referred to, in general, as digital rights management systems.
One digital rights management technique is referred to as “bit stripping.” In bit stripping, a content server removes a portion of the information from a media content file. The removed information is stored in a “recombination file,” and the remaining information is stored in a “stripped file.” In general, the recombination file might be around 1%-2% of the size of the stripped file. The selection of data that is stripped from the media file may be different for each authorized recipient of the file. In this way, the recombination file is a sort of “key,” unique to each recipient, that can be used to unlock that recipient's version of the stripped file. Such a system may be used in, for example, streaming media applications. A streaming media player may be responsible for processing the recombination file and the stripped file back into usable digital media content as that content is being played back to the user. The streaming media player does not write the recombined, usable digital content onto the recipient's hard drive, so the recipient does not obtain a copy of the content that he can freely distribute to other users.